Cancer Terminology

Cancer has its own language that is unfamiliar to most people when they are newly diagnosed. Our volunteers and staff are happy to help you understand the terms listed below or any other terminology that you may encounter.


General Terms

Benign: Not cancer.

Cancer: Abnormal, uncontrolled growth of cells of any organ of the body. Cancer is not one disease, but over 100 different diseases. (Breast cancer, for example, is a different disease than colon cancer).

Malignant: Another term for cancer.

Tumor: An abnormal mass of tissue. Tumors may be benign (not cancer), or malignant (cancer).

Metastasis: The spread of cancer from one part of the body to another.

Pathology Terms

Stage: The extent of a cancer in the body. It is based on the size of the tumor and whether it has spread. Stage 1 is early stage and Stage 4 is the most advanced stage.

Grade: how abnormal the cancer cells look under a microscope and how quickly the tumor is likely to grow and spread. High grade tumors tend to be more aggressive than low grade tumors.

Margins: When a tumor is removed, it’s examined to determine if the borders of the tumor are cancer-free. If there are cancer cells on the border, more surgery may be required.

Testing Terms

CT Scan: a series of X-ray that are combined by computer into images of the bones and soft tissues inside your body. CT scan images provide much more information than do plain X-rays.

MRI: Another imaging device that is especially useful in viewing the brain, spine, the soft tissue of joints, and some other parts of the body. MRIs do not use X-Rays.

PET Scan: Unlike CT and MRI which look at structures (i.e., the architecture of the body), PET looks for cancerous activity. Cancer cells often “light up” on a PET Scan because they metabolize glucose differently than do normal cells. PET scans are often used to see if cancer has spread to other parts of the body.

Ultrasound (Sonogram): Uses sound waves to identify tumors and other structures within the body.

Tumor Markers: blood tests that may indicate the presence of certain cancers in the body. The PSA test for prostate cancer is a tumor marker. Not all types of cancers have tumor markers.

Treatment Terms

Chemotherapy: Treatment with drugs that kill cancer cells.

Radiation Therapy: The use of radiation from x-rays and other sources to kill cancer cells and shrink tumors.

Hormone Therapy: Treatment that blocks, removes or adds hormones to slow or stop the growth of certain cancers (such as prostate and breast cancer). Tamoxifen and Lupron are examples of hormonal therapies.

Targeted therapies: Newer drugs that specifically target cancer cells while doing minimal damage to normal cells. Herceptin is an example of a targeted therapy.

First Line Treatment: the initial treatment that is used to treat a patient’s cancer.

Second Line Treatment: a treatment that is started when the first-line treatment stops being effective. (There are also third-line treatments and so on).

Source: Adapted from the National Cancer Institute Dictionary of Cancer Terms.

Further Resources

National Cancer Institute Dictionary of Terms

The Alphabet Soup of Health Care Providers (What do all of those initials stand for?)